Camera sextant



sept. 2 1,930. M. R. PIERCE .Re 17,790 CIIAJVIERA SEXTANT iginal Filed March 5,- 1925 3 sheets-sheet 1 y M. R. PIERCE sept' 2f 1930- CAMER'A sExTANT Re 17,790

. y 2 original Filed March 5, 192s 5 Sheets Sheet I QQ .n u) 02 ||||||||||||||||||||||||||||||||||||||||||||||||||||I|I|||||||||||||||||||||||||||||||||||||l| I ||||||4I||||||||||||||||||| |||||||||||||i||||||||||l||||||||||| l M. R. PIERCE CAMERA SEXTANT s sheets-sheet s sept. 2, 1930.

Original Filed Mazfch 5. 1926 frzkuw 5.... mz.

e zerce Aztorfey Reissued Sept. 2, 1930 UNITED STATES PATENT oFFlcl;

MAURICE B. PIERCE, OF THE UNITED STATES NAVY, LAKEHUBST, NEW JERSEY CAMERA SEXTAN T Original No. 1,658,585, dated December 20, 1927, Serial No. 92,655, filed March 5, 1926. Application for reissue nled September 6,

This invention relates to improvements in sextants, particularly adapted for use on aircraft where it becomes necessary to take readings from'a celestial body and an artificial horizon at times when the natural horil zon is not visible.

Before going into the details of the present invention it may be well to note that in taki ing altitude readings from the aircraft with various types of sextants now in use, the great diiiicultyhas been experienced in that when concentrating on centering the horizon level, the image of the celestial body usually disappears from the finder, and when concen- |5 trating on bringing the image back to its y proper position on the finder, the level is displaced, making it extremely difficult to obtain an accurate reading without great range of error.

It is, therefore, one of the objects of the present invention to overcome this difficult and to make a permanent record with bot objects appearing thereon in -order that proper corrections may be made and an accurate determination obtained.

A further object is to provide a sextant of the above character,- of simple and practical construction, whereby a photographic print or record may be easily and quickly l,procured. A further object of the present inven- 'tion is to provide 'an apparatus of the above character which may be conveniently operated, which will be of light and compact construction, and which may be inexpensively manufactured.

Other objectshwill bein part obvious and ir part hereinafter pointed out in connection with the accompanying sheets of drawings 4o illustrating two of various possible modifications and wherein similar 'reference characters denote corresponding parts. Int these drawings,

Fig. 1 is a diagrammatic view of a camera 4.? sextant, certain parts being broken away, certain parts, such as partitions being omitted, and certain other artsfshown con-y ventionally for clearness o illustration.

Figure 2 is an enlarged view of the grid used in the preferred` form, showing com- 1928. Serial No. 304,343.

bined grid and template, having the etched graduations and reference lines which are projected to the photographic print when the images are snapped.

Figure 3 is a view of the exposed photographic print made with the preferred form, showing a position of the horizon bubble image, celestial 'body image, reference lines and graduations for a complete correction a reading.

Figure 4 is an enlarged view of the grid used in the modified form, showing the reference lines which are projected to the photographic print when the images are snapped.

Figure 5 is a view of the exposed photographic print made with the modified form, showing a position of the horizon bubble image, celestial body image, and reference lines projected through the grid.

Figure 6 is a view of the template to be placed over the modified point shown in! Figure 5for taking readings for correction from the positions of the image.

In the preferred form of this invention a true reading of altitude is obtained by roughly noting the angle of the setting of the prism lens, a positive correction reading from the horizontal image on the print and a positive correction reading from the celestial body image on the print. The horizon bubble image reading gives the true correction for not getting the sextant level, and the celestial body image reading gives the true correction for not centering in the finder sight.

The shadowgraph image, reference lines and graduations for reading the corrections are projected through the etched grid plate` and the readingstaken directly from the photographic print (direct in the preferred form). ci

In the modified form of this invention a true correction reading is obtained as before, by roughly noting the angle of the set# lting ofthe prism lens, by noting a positive f correction reading from the horizon image, from theprint, by placing an engraved transparent template over the print, and by reading the correction for true altitude from a celestial body.v

The reason for having an alternative con- 10J to be understood that while the horizon bubble level has been shown as a means of illustration, it hasbeen contemplated touse any other type of level gauge if preferred. A pendulum, gyro-compass or the like may be used without departing from the invention.

By means of reflecting mirrors the images may be photographed in the same manner.

It is preferred, however, to use a liquid level to further reduce possible error and to save expense and weight in installation.

Referring to the drawing, the character 1 indicates a housing'y for inclosing the various parts having an opening 2 through which the image of the sun or other celestial body may pass, and it is understood that the casing includes conventional structural parts such as partitions and the like, for preventing clouding ofthe sensitized surfaces from for-v eign light sorces. Theimage is reflected by a rotatably mounted prism 3' bearing a pointer that operates'over graduations for indicating the angle of the setting of the prism, and then passes on through a lens 4.

vWhen the shutter 5 is operated, the rays pass on to a reiection prism 6 andare there reflected to a sensitized paper 9. 4 The image of an artificial horizon indicator, or as illustrated, a bubble horizontal level 7, is also projected on the sensitized paper by the light rays reflected through the prism system. The

intensity of the image of the artificial horizon indicator is increased vby artificial illumination Within the camera casing by any Well lmown means such as an electric light. 7,

' that is automatically vswitched on at the in@ Y the illuminatin stant the shutter is operated. The Vcurrent for the light may be `supplied from batteries housed in the casing, or. from any outside source if preferred. It Will therefore be seen that as the rays are projected through the etched grid plate 8, a shadowgraph image of the celestial body, horizonlevel image, reference lines, ,and graduations are recorded on the sensitized paper strip., This strip is fed from the roll 9 in any well known manner, severed by acutter 1l, and stored ina transfer-container 12. The lexposed prints may be collected v,until the "desired number of snap shots have been taken, and may then be developed in the usual manner.

A stop watch 21, and control switch 18 for lamp are simultaneously controlled by t e shutter operating button 20 j I ,l

window 22 is located at thebottoin ofthe Vcasing'l `for'autographing the date, time, and.

When the grid angular setting of the prism lens on the back of the film for identification after developing.

The grid plate 8 may contain all the graduations for determining the` correction readings by projecting the same to the print, see Fig. 2, or may bear certain reference or base lines as indicated in Fig. 4. The scale etched to the leftv is for reading the bubble horizon correction, and represents a horizontal base lineI and the graduations of the scale indicate two and one-half minute intervals. The graduations to the right of the vertical reference line are used to determine the correction for the celestial image, and representintervals of fifteen seconds. f

When the grid and template are combined as in the preferred form, all graduations will appear on the print, and the readings are taken directly from the print, but when the grid plate only bears certain reference linesv and the template bears the graduations, the print after being developed is placed on a flat surface, with the horizon image to the left, and the template moved about until one of the vertical lines on the print which was projected from the reference line on the grid, registers with the lines on the template and the horizon level image is centered under either of the two groups of three short parallel lines indicating -I-r or The horizontal reference line on the print is used toread the true correction for not holding the sextant level. The template is then shifted to regis- -ter the image of the celestial body on the print, under the diagonal line on the template, and the correction for not getting the celestial body centered in the finder is read from the reference line on the print either or The combined readings will then ascertain the true altitude reading from -a celestial body.

It may be useful to remember that when the horizontal level image, and the image of a celestial body are above the reference or base line on print, the plate intervals are In order to sight the instrument, two focal systems are necessary, one as previously described for Vrecording lthe celestial image andthe other to center the reflection of the celestial body in a finder.

Located at the opning 2 is a smaller prism 30 operated simultaneously bythe same rotating and angle reading graduations as the prism 3. JThe prism 30"is located to one side of the path of the main lens focal system, so that the 'reflection of the celestial image is deflected by the prism 30. to a fixed-prism 3l fwhich directs the image to a fmderl32 located on top of the sextant, in a convenient position to be sighted bythe'eye;

- The speer 32 is shadedb 33 to soften the brightest reI cations fromothe4 observerys' eyes/ Theflnder is'also provided with bubble levels `andj for :further `aid p,

in bringing'theerror of correction 1g); a. minia fremd glass..

.the problem easily and quickly solved.

The invention is, therefore, believed to accomplish, among others, all of the objects and advantages herein set forth.

What I claim is 1. A sextant camera including a casing provided with an opening for the admission of light to the'interior of the casing, means normally excluding the light, prisms Within the opening, other prisms Within the casing on the opposite, side of the shutter, a hori-l zontal level, a grid, and means for supporting a sensitized paper for the reception of an image of a celestial body, an image of the horizon and an image ofthe grid When the shutter is opened.

2. A sextant camera including a casing, a

. finder, means for supporting a sensitized paper in the casing, a focal system for projecting the image of a body to the finder, a focal system for simultaneously projecting the said image to the sensitized paper, and a single meansfor excluding the image from both the finder and the paper.

3. A sextant camera including a casing, a finder, means for supporting a sensitized paper in the casing, adjustable prisms mounted in the Wall ofthe casing, means for determining the angle of adjustment of the prisms, a plurality of fixed prisms Within the casing for simultaneously deflecting the image projected by the adjustable prisms to the `finder and sensitized paper, and means for normally excluding light from the casing interior.

4. In a sextant camera, the combination of a casing, having an opening therein, a plurality of rotatable prisms Within the opening, ailens, ashutter, a plurality of fixed with the rotatable prisms and lens, a finder disposed at a point optically opposite one of the fixed prisms, and means disposed optically opposite the otherof the fixed prisms for recording an Vimage focused thereupon bythe lens.

5. A sextant camera including a casing, a

plurality of movable prisms, a lens, a shutter, a finder, a plurality of fixed prisms, an arti .ficial horizon, a template, and means forsimultaneous recordi-ng of an image of abody,

\ the artificial horizon and the template.

6. A sextant camera .including a casing provided With an opening, a prism at the opening, another prism Within the casing, a.

shutter therebetween, a horizontal level, a grid, and means for supporting a sensitized member for the reception of an image of a celestial body, an image of the horizon and an image of the grid When the shutter is opened.

7. A sextant camera provided with a finder, means for supporting a sensitized member, a focal system for projecting the image of a dist-ant body to the finder, a `focal system for simultaneously projecting the said image to the sensitized member, and a control means for excluding the image from and exposing the image to the member.

8. A sextant camera including a casing, a finder, means for supporting a sensitized paper in the casing, adjustable prisms for receiving light from a distant body, means for determining the angle of adjustment of the prisms, and a plurality of fixed prisms Within the casing for simultaneously deflecting the image projected by the adjustable prisms to the finder and to the sensitized paper.

9. In a sextant camera, the combination of a casing having an opening therein, a plurality of rotatable prisms Within the opening, a plurality of fixed prisms Within the casing and in alignment With the rotatable prisms, a finder disposed at a point optically' opposite on of the fixed prisms, and means disposed optically opposite the other of the fixed prisms for recording an image received from the other of the fixed prisms.

10. A sextant camera including a casing,

a movable prism for receiving light from a distant body, a fixed prism, an artificial horizon, a template, and means for simultaneous recording of an image of the body, the artificial horizon and the template.

l1. A sextant camera provided With means forming an optic path, said means including a prism adapted to receive light from a distant body and change its direction as it enters the camera, means for indicating the angle of said change in direction of the light ray, means Within the camera for directing the light along a fixed path, anarticial horizon and a grid disposed insaid fixed path said grid' having points of reference thereon and means for simultaneously recording of an image of said distant body, the artificial horizon and said points of reference from the rid. .g l2. In a sextant camera, the combination of means for locating a sensitized member in causing said `two optical means and said time indicator to function simultaneously.

13. In a seXtant camera the combination of a locating device supporting a sensitized member in a plane ot reference adapted to be tilted with thecainera from a horizontal plane, means for photographically recording on the sensitized member the angle between said plane of reference and the liorizontal plane, and means functioning simultaneously with the tirst mentioned means for photographically recording on the sensitized memberI a correction to .be applied to an assumed angular value approximating the angle foi-med between a distant body and said plane ot reference at the instant the recording is made. y

14. In a sextant camera the combination of means for supporting a sensitized ineinber in a plane of reference, means forming an artificial horizon, a grid provided with two lines of graduations parallel to each oth'- er and spaced apart in one direction from a zero line, said artificial horizon means and said grid coacting to position the image of said horizon at said zero point when said plane of lreference is lixed relative to the true horizon, and lpositioning the image of the horizon along one of said lines of graduations and -spaced from the zero point distances proportionate to the angles between the true horizon and said plane of reference, and means for positioning on said sensitized member and in juxtaposition to the other line of graduationsan ima-ge of a distant body.

15. In a sextant camera, the combination of means defining a plane of reference adapted to be tilted at van angle to the true horizon, means for directing a light ray from a distant body on to said plane, means for recording the angle between said plane and said true horizon, means for recording the angle between said plane and the portion of the light ray .impinging on the saine, and control means for causing both of said recording means to function simultaneously.

1G. In a s 'xtant camera, the combination ot' means d ining a plane of reference adapted to be tilted at'an angle to the true horizon, means for directing a light ray from a distant body on to said plane, means for recording the angle between ysaid plane and lsaid true horizon, means for recording the angle between said plane and the portion of' clinometer contained within the casing and visible to the operator, and manually actu-.- ated means carried by the casing for simultaneously indicating the time and for recording an image of the reading of said contained inclinometer.

18. In a device of the class described, the combination ot a4 shiitable cameia seXtant provided with a casing having sighting means adapted to be trained on a distant body, manually adjustable means including a scale graduated in angular degrees carried by the casing for indicating approximately the angle between the horizontal and aline determined by the training of said sighting means on the distant body, an inclinometer'housed within the casing for indicating a correctionftobe applied algebraically to said approximately Vindicated angle, and means for photographically recording the readings of the inclinometer. v

19. A camera sextant provided with means for sighting a distant body, means including Va lens provided with a manually adjustable scale and pointer and a correcting inclinometer and associated scale collectively indicating the 4angle of altitude of said body,A 'a time indicator, means for photographically recording an image of the inclinometer and tion from the horizontal of Va. distant body,

the combination of a support adapted to be held substantially in a horizontal position and to be moved manually in training the device on the distant body, sighting means for viewing the distant body, carried by the support and movable therewith, photographic means carried by the support, means for 1ndicating the angle between the true horizon and the line of sight through said sighting means, said indicating means including graduated scales and coacting indicators visible to the operator and certain readings of said indicating means being exposed to said photographic means.

21. A device -for indicating the angular variation from 'the horizontal of a distant body, comprising. a casing, sighting means carried.V thereby and movable 'therewith for viewing the distant body, means for indicating approximately the said angular variation,

and means for recording the angle of correction between the reading of said approximate angular indicating means' and the true angular variation of the distant body from thehorizontal. I

22.\In a device for recording the angle of elevation or depression from thehorizontal of a distant body, the combination of a casing,

spirit level rom a position exteriorly of the casing, means within the casing for illuminating the spirit level, means for photographing the spirit level and its scale and a manual- 1y actuated control for said photographing means. Y

23. In a device for recording the angle of elevation or de pression from the horizontal of a distant body, the combination of a casing, sighting means carriedfby the casing and movable therewith for viewing the distant body, an inclinometer support adapted to be moved with the casing, an inclinometer mounted on the support for indicating the angular variation of said support from the position which it assumes when the casing is in its normal horizontal position with the sighting means directed to av distant body in the horizontal plane containing the device and means for photographically recording the reading of angular variations as indicated by said inclinometer.

'24. I-n a device of the class described, the combination of an enclosed casing adapted to be tilted from' a normal horizontal position about a horizontal axis when in use, sighting means adapted to be trained on adistant body, a spirit level contained within thel casing, a graduated scale coacting with the spirit level to indicate angular variationsA of the casing from its normal horizontal position, a. source of light contained within the casing for illuminating the spirit leveland its scale and manually controlled means for photographically recording the illuminated spirit level and scale whereby a photograph of the spirit ylevel reading may be made at the instant of time when the distant body is visible through the sighting means.

25. Ina camera sextant, the combination of a casing including means providing a plane of reference which may be tilted in tilting the camera from a horizontal, sighting means adapted to be trained on adist-ant body, means for indicating the angle between said plane of reference and the line of sight leading to the distant body, corrective means comprising an inclinometer and associated scale graduated in degrees carried by the casing indicating automatically the angle between said plane of reference and the horizontal and means for photographically recording the reading of said inclinometer and its scale.

26. In a device of the class described, the combination of a casing which is liable to be shifted from its normal horizontalposition while in use, sighting means carried thereby and adapted to be trained on a distant body,

means for indicating the angle in a vertical plane between a line passing through the distant body and any arbitrarily selected plane of reference shifted with the .camera from its normal horizontal, means for indicating the angle between said selected plane of reference and the truehorizontal, and means for photographically recording said last named indications.

27. A celestial surveying device comprisin g sighting means adapted to be trained on a celestial body, instruments for supplying time and other data necessary for making celestial observations, said instruments including a time indicator for registering any instant of time at which the instrument is caused to function, an inclinometer controlled automatically by a shifting of said sighting means in space, means for photographically and'instantly recording the readings of certain of said kinstruments and a manually actuated control for causing said device to function at will and whereby the operator can automatically obtain the requisite data by actuating the control at the instant he sees the distant body through the sighting means.v

28. In a camera seXtant for use in celestial geometry. the combination of a casing adaptved to be disposed in an approximately level position while making an exposure, manually controlled sighting means carried by the casing, and adapted to be trained on a celestial body. means for indicating the altitude angle vof said body including an inclinometer and .said photographing means to cause the same to function simultaneously whereby the opn erator may obtain a record of the altitude angle and the time at which the observation was made at the instant-the light from' theI celestial body is seen in the sighting means.

` 29. In a camera seXtant for rcgording an altitude observation of a distant brdy and for indicating the time at which the observation is made, the combination of an enclosed casing adapted to be disposed in position defining a horizontal plane of reference. sighting means carried by the casing. movable therewith and adapted to be trained on a distant body, an inclinometer including an indicator and its associated scale mounted within lthe casing, said scale having a horizontal base line and graduations in degrees extending from one side of the base line, said inclinometer and its scale being associated so that the indicator of the inclinometer will be at the horizontal base line position on the scale when the casing is disposed in position to define said horizontal plane and indicating in degree readings on the scale the inclination of the casing from said horizontal plane dening position, said casing provided with an opening exposing the inclinometer so that .it is visible to the operator, a time indicator carried by the casing and visible to the operator, means carried within the casing for photographically recording the readings of the inclinometer on the scale and control Vmeans adapted to be actuated by the Ioperator at the instant the sighting means are trained on distant body, with incidental inclination ofthe casing as a whole, for causing the last named means to function.

3). In a camera sextant, the combination of an enclosed casing, sighting means movable with the casing and adapted to be trained on a distant body the altitude angle of which is desired, and acting to direct the light from said distant body through the casing to the eye of the operator, a manually controlled angle meter adapted to be preset to indicate approximately the altitude angle of said distant body when viewed through the sighting means with the casing approximately in its normal horizontalposition, an inclinometer and an associated scale housed within the casing for indicating the inclination ofthe casing from said normal horizontal position, means within the camera for illuminating said inclinometer and its scale, means for photographically recording the readings of said illuminated inclinometer and scale and a manually actuated control for effecting the functioning of said recording means whereby the operator may obtain a permanent rec- 'ff ord of the variations to be added algebraically to the preset readin s of the angle meter necessitated by any inc ination of the casing at the instant the observation was taken thereby to obtain the true altitude angle of the distant body irrespective of any displacement of the casing from its intended khorizontal position.

l Signed at New York inthe county of New York and State of New York, this 23rd day of August, A. D. 1928. f

. MAURICE R. PIERCE. 

